In 1975, Hamberg et al discovered an unstable intermediate in the conversion of prostaglandin G2 into the hemiacetal derivative in platelets [Proc. Nat. Acad. Sci. U.S.A., Vol 72, No. 8 page 2,994 (1975)]. This intermediate has been named thromboxane A.sub.2 and its structure has been proposed as follows: ##STR2##
TXA.sub.2 has been found to show various biological activities such as platelet aggregation, aorta contraction and thrombi formation and therefore is considered to be one of the causes by which diseases such as inflammation, thrombus and cardiac infarction are induced.
Some TXA.sub.2 analogues are proposed as compounds having antagonistic activity on TXA.sub.2 ; for example, compounds where the oxygen atoms at the 11a- and 9,11-epoxy-position of TXA.sub.2 are replaced by carbon atoms [see Japanese Patent Kokai No. 55-143930], and compounds having a pinane skelton [Proc. Nat. Acad. Sci. U.S.A. Vol. 76, No. 6, page 2,566 (1979)]. The compounds described below which have a cyclopentane skeleton are also known. ##STR3##
More recently, in the specification of GB No. 2184118, the carbocyclic sulfonamide derivatives of the general formula: ##STR4##
wherein R.sub.1c represents a hydrogen atom or lower alkyl group,
R.sub.2c represents an alkyl group, substituted or unsubstituted aryl group, aralkyl group or heterocyclic ring,
R.sub.3c represents a hydrogen atom or methyl group,
Xc represents a alkylene group or alkenylene group substituted by one or more fluoro atom(s) or, containing one oxygen atom, sulfur atom or phenylene group,
Yc represents a straight-chain or branched-chain alkylene group or alkenylene group, oxygen atom or sulfur atom,
mc represents an integer of 0 or 1, and
nc represents an integer of 0, 1 or 2 have been disclosed. The following compound was published by Bayer A. G. at 16th International Symposium on the Chemistry of National Products opened on May 29-Jun. 3, 1988.